Obesity: A Complicating Factor for Sedation in Children

Resident’s Name: Jessica Wilson

Program: Lutheran Medical Center - Providence

Article title: Obesity: A Complicating Factor for Sedation in Children

Author(s): Baker & Yagiela.

Journal: Pediatric Dentistry

Year. Volume (number). Page #’s: 2006. 28:6. 487-493.

Major topic: Obesity and Sedation

Overview of method of research: Lit Review

Background:
The incidence of mortality of pediatric sedation has been estimated to be 1:250,000. The major cause of serious negative complications is hypoxia and often involves healthy patients. However, patients with compromised respiration are more likely to have complications. Obese patients are considered to have “chronic extrinsic restrictive lung disease” on top of other compromised systems.
In adults a BMI >25 is considered overweight, >30 is obese and 40 or more is morbidly obese. In children, these ranges vary by age and gender (see chart).

Obesity’s Biological Consequences:
Respiratory System: Obesity restricts ventilation by adding excess weight to the thoracic and abdominal cavities making movement of the diaphragm more difficult as well as increasing airway resistance. The functional residual capacity, the amount of gas remaining in the lung after passive expiration, decreases exponentially when BMI increases. These changes are heightened with the use of respiratory depressant medications creating a smaller oxygen reservoir. Obese patients also tend to breathe more rapidly and shallowly which is only further accentuated in pediatric patients who have a higher respiration rate. Increased weight promotes airway narrowing and estimated 5% of obese patients develop obstructive sleep apnea.
Cardiovascular System: Although obesity can have negative effects on the cardiovascular system, cardiovascular complications due to obesity alone during sedation are rare with pediatric patients.
Gastrointestinal System: Obese pediatric patients tend to have a high gastric volume increasing their risk of aspiration. A short neck, minimal movement of the cervical spine and limited mouth opening from fatty cheeks and submental region as well as large tongue can also complicate sedation.

Pharmacokinetics in the Obese:
BMI affects drug absorption, distribution, metabolism and excretion especially lipophilic drugs which include most drugs used for sedation. Intravenous doses of drugs tend to have similar initial effects, but a shorter duration of clinical effect due to redistribution to adipose tissue. Once the administration has stopped, there is a longer elimination half-life causing a delayed complete recovery.
Sedation drugs administered orally also tend to have increased initial effects with an extended clinical duration. Although nitrous oxide has a relatively rapid onset and elimination, recovery time for the obese patient can also be delayed.
Disturbances in liver and renal function can have effects on drug clearance, but sedation after single doses are not usually affected.

Recommendations:
Thorough medical evaluation looking for signs of respiratory disease or cardiovascular disorders as well as range of motion in the neck and jaw. Oral sedation should be carefully monitored and although dosages are typically calculated by total body weight, maximum dosages should be reduced.
Nitrous oxide is a good option while opioids and chloral hydrate should be avoided because of their tendency to cause excessive sedation.
Fasting regulations set by the AAPD should be strictly enforced. Obese patients should be monitored with a pulse oximeter, blood pressure cuff, pretracheal stethoscope, electrocardiogram and capnograph. As hypoxemia is a common complication, patients should be closely monitored post-operatively in a somewhat upright position and not released until they remain awake without stimulation. Post-operative opioid analgesics are to be avoided and lastly, a chest x-ray should be taken if aspiration of stomach contents is suspected.

Assessment of Article:
Me really likey. This article points out a bunch of information that makes sense, but I never thought about before. Very interesting for us as pediatric dentists especially considering the increasing numbers of obese children.